KANSAS CITY, Mo. >> By almost any measure, Chiefs quarterback Alex Smith is having the best season of his career.

Best season of anybody in the league this year, too.

He was 29 of 37 for 324 yards with three touchdown passes and no interceptions in Sunday night’s 42-24 victory over Houston, which kept Kansas City as the NFL’s lone unbeaten team. That was good for a 130.2 passer rating, his sixth straight regular-season game with 100.0 or better.

His prolific night tossing touchdown passes followed a four-touchdown performance in the season opener against New England, and gave him 11 for the season, third best in the league.

Smith also ranks third in yards passing, better than such notables as Aaron Rodgers, Philip Rivers and Ben Roethlisberger. He ranks first in completion percentage at 76.6, more than 5 percent better than Josh McCown in second. And he ranks first in yards per attempt at 8.80, topping second-place Tom Brady, even though Smith has been saddled with a dink-and-dunk reputation as a game manager.

Oh, and he’s run for more than 100 yards and another touchdown during the Chiefs’ 5-0 start.

“He’s really good at extending plays,” Texans coach Bill O’Brien said. “I’m not sure what he rushed for, but he ran for a lot of yards. He’s a great player. He’s playing at a high level right now.”

The Chiefs are playing at a high level because of him.

This is the third time in franchise history the Chiefs have won their first five games, and the win in Houston was their ninth consecutive on the road, matching the franchise record set in 1966-67.

Since his arrival in a 2013 trade with San Francisco, Smith has helped the Chiefs piece together a win streak of at least five games during each season. That included nine straight to start the 2013 season, 10 straight two years ago and five in a row to win the AFC West last season.

“Alex is playing similar to how he’s played before. The results are a bit different,” Chiefs coach Andy Reid said. “It seems like he’s more in tune, and the receivers are more in tune with their games with one another. (Offensive coordinator) Matt Nagy has done a phenomenal job as a coordinator and putting things together that are Alex’s best stuff.”

The fact that Smith has played at this level is remarkable considering the injuries that have ransacked the offense. They’ve been without center Mitch Morse and guards Parker Ehinger and Laurent Duvernay-Tardif, left tackle Eric Fisher has played through some back spasms, and more injuries hit during an otherwise dominant performance in Houston.

Tight end Travis Kelce was sidelined by a concussion, briefly returned to the game, then left again when he complained of memory loss. The Chiefs also lost No. 2 wide receiver Chris Conley with a ruptured Achilles tendon, further depleting a young and not necessarily deep position group.

None of that seems to have mattered, though. Smith just keeps making plays.

“I think we’re just executing more consistently,” he said. “I think we’ve had flashes in years past and I think we’ve had a good stretch week to week. I think we have a confidence about us that even when we do get little spills and things don’t go our way, we still can find a way to go back to being us. We have the guys to do that. We have the coaches to do that. We have the confidence in that.”

No mistake, the Chiefs are exuding confidence heading into next Sunday’s game against Pittsburgh, the team that knocked them from the divisional round of the playoffs last season.

That’s because the biggest question mark surrounding the Chiefs the last few years has been the ceiling of their quarterback. Everybody knew that their defense was stingy and opportunistic, and that playmakers such as Kelce, wide receiver Tyreek Hill and now rooking running back Kareem Hunt gave Kansas City enough weapons to stay in the game with anyone.

What most people still questioned was whether Smith could carry a team on his right arm.

So far, he’s answering their question with aplomb.

NOTES: Reid said during a conference call Monday that Kelce was feeling better but still must go through the NFL’s concussion protocol. … Reid also praised RG Cam Erving, who started for Duvernay-Tardif in Erving’s first game since arriving in a trade with the Cleveland Browns.